Federal prosecutors said in a court filing entered last week that they agree with the defense for Joshua Stafford of Cleveland that the results were inconclusive on his mental competence.
But the government said a hearing before a federal judge in Akron should provide evidence that Stafford is mentally fit to stand trial. No hearing date has been set.
No bomb went off and no one was hurt. The four other defendants have pleaded guilty.
The target was a highway bridge over the Cuyahoga Valley National Park between Cleveland and Akron. The FBI said the device was a dud provided by an informant.